The use of devices for mounting machine elements, such as pulleys and gears, upon a shaft is well-known. One difficulty is that the known devices for mounting a machine element upon a cylindrical shaft are cumbersome to use. For example, some devices require assembly of multiple pieces and adjustment of several screws, and other devices require modification of the shaft on which the machine element is mounted.
Another difficulty frequently encountered relates to the need for precise positioning of the machine elements circumferentially and/or axially on the shaft when the machine element is mounted upon the shaft. Specifically, it is desirable to position the machine element at a particular axial position and maintain the element at such position after the element is attached to the shaft. In addition, it is desirable to allow for the infinitely-variable adjustment of the machine element circumferentially prior to attaching the element to the shaft.